In recent years, an image pickup apparatus tends to increase in the number of pixels. Further, there is an increasing demand for high-speed reading of image data as the number of cells is increased by reduction of cell size or so as to adapt to a moving image and the like.
To meet the demand, there has been proposed an image pickup apparatus in which a plurality of pixels (photoelectric conversion elements) adjacent to each other share part of electrical construction therebetween (see e.g. PTL (Patent Literature) 1). For example, a floating diffusion unit (FD) (211), a MOS amplifier (212), a selection switch (213) and a reset switch (210) are shared between photo diodes (202 to 205) of the respective pixels and transfer switches (206 to 209) (see FIG. 3).
Here, in an image pickup device used in the image pickup apparatus, defective pixels are sometimes generated e.g. in a manufacturing process. Outputs from the defective pixels are different in output level from other normal pixels, causing image quality degradation.
On the other hand, there has been proposed a technique of correcting defective pixels of the image pickup device, information on which is stored in advance, checking the image pickup device as occasion demands to thereby extract defective pixels different in pixel output from the other pixels and store information thereon, and correcting the new defective pixels thus extracted as well (see PTL 2).
Further, there has been proposed another technique of correcting defective pixels in real time, by extracting defective pixels based on a difference in signal level between a predetermined pixel of an image picked up and pixels of the same color adjacent to the predetermined pixel, and a difference in signal level between pixels of the same color of a different kind existing around the predetermined pixel (see PTL 3).
Furthermore, there has been proposed still another technique in which when storing the address of a defective pixel, there are stored not only the address of the defective pixel but also a bit of data for determining whether a plurality of defective pixels occur in succession thereto, whereby as for defective pixels occurring in succession, only the address of a leading one of the defective pixels is stored (see PTL 4).
Further, a phenomenon is known in which the increase in number of the pixels of the image pickup apparatus produces pixels suffering from a flickering defect in which when the image pickup device is repeatedly read out under the same conditions (the same temperature, the same accumulation time period, and light blocking), the dark charge level of an image signal read out undergoes extreme rises and falls (see PTL 5).